The present invention relates, in general, to mechanical linkages, and has applications in the fields of automotive, general mechanical, and civil engineering. In the field of automotive engineering, the present invention has particular applications in automotive power train engineering and engine throttles.
A mechanical linkage having two ends can be used to transfer an input force at one end to an output force at the other end. In applications that require a varying force at the output end of a mechanical linkage, a varying force can be provided at the input end by a variable torque actuator or motor attached to the input end. However, variable torque motors are expensive and can be difficult to operate for providing the desired variable output force. Therefore, in applications that require a varying output force, there is a need for a mechanical linkage system that can provide a varying output force without the use of expensive variable torque motor.
In the field of automotive engineering, engine throttle control typically requires a variable torque motor operatively connected to a throttle valve in an automotive throttle. An automotive throttle for regulating the delivery of intake air to the manifold of an internal combustion engine generally comprises a throttle body with a butterfly valve rotatably mounted within its bore. The configuration of the throttle body and the butterfly valve have been identified as apparently giving rise to mechanical resistances when the valve is close to the bore of the throttle body (i.e. when the valve is nearly fully closed), the plane of the valve approaching perpendicularity relative to the longitudinal axis of the throttle body. The resistances are believed to be due to ice or other contamination that can form in the small clearance between the butterfly valve and the throttle body inside diameter when the valve is nearly fully closed. Furthermore, the pressure drop across the valve approaches its maximum value when the valve approaches the nearly closed position. Therefore, to overcome the above mentioned mechanical resistances of the butterfly valve in the nearly closed position, the butterfly valve can be operatively connected to a variable torque motor. The variable torque motor can be configured to provide a relatively greater amount of torque at the valve nearly closed position than the torque needed at a valve partially or fully opened positions. However, there still remains a need for a throttle control system that can operatively control the butterfly valve in an automotive throttle without the use of expensive variable torque motors.
The present invention offers a solution to the foregoing problems by providing an assembly for providing a variable output torque based upon a constant input force. The assembly includes an actuator for providing a constant input force and at least one link operatively coupled to the actuator and to a pivot point such the constant input force is converted to the variable output torque.
The present invention also provides an assembly for providing a variable output torque based upon a constant input force. The assembly comprises first and second links each having a first end pivotally mounted about a respective axis and each having a second end operatively coupled together an additional link, each of the first and second links having a different angular orientation relative to an imaginary line extending between the axes; and an actuator driving the first link pivotally about its axis at the constant input such that the second link is driven pivotally about its axis at the variable output.
The present invention also provides an assembly for controlling the position of a throttle valve rotating about a first axis between a first position and a second position. The assembly comprises a motor for moving an actuator between two positions; and at least one link coupling the actuator and to the valve and imparting to the valve a first torque when the valve is in the first position and a second torque when the valve is in the second position, the second torque being less than the first torque.
The present invention also provides a method for controlling the position of a throttle valve. The valve is pivotal about an axis of rotation. The method comprises applying a first torque with an actuator to the valve when the valve is in a first position; and applying a second torque with the actuator to the valve when the valve is in a second position.
The present invention also provides a method for determining the position of a valve in a throttle. The valve is driven by an electric motor and a relationship has been established between the current drawn by the motor and the position of the valve. The method comprises measuring the current drawn by the motor; and determining the position of the valve from an established relationship between the current drawn by the motor and the position of the valve.